One such radiator unit is disclosed in US 2015-0167532 A1. If the smaller radiator does not completely fill out the cross section of the air duct, it inherently makes sense to mount on a side of the air duct rather than centrally in the air duct.
Air flap arrangements with a plurality of air flaps are known for metering the cooling air flow, which can be swiveled together out of an open position that does not restrict the cooling air flow. The farther away these flaps are deflected from the open position, the more they limit the air flow, but simultaneously divert it to the side. If this side is the one on which the first heat exchanger is mounted, the limited air flow is concentrated thereon, and the limitation predominantly affects the second heat exchanger. Conversely, if it lies opposite the side on which the first heat exchanger is mounted, the air flow through the first heat exchanger is diminished to a significantly greater extent than through the second one. In both cases, the distribution of cooling capacity to the heat exchangers clearly changes as a function of the air flaps.